I found another example where Nero AAC produces regression artifacts when moving from -q 0.50:
-q 0.50
foo_abx 1.3.4 report
foobar2000 v1.1
2010/09/06 22:51:32
File A: C:\Rips\Kraftwerk - Techno Pop\01. Boing Boom Tschak.flac
File B: C:\Temp\Boing Boom Tschak q 0.50.m4a
22:51:32 : Test started.
22:51:50 : 01/01 50.0%
22:51:55 : 02/02 25.0%
22:52:00 : 03/03 12.5%
22:52:06 : 04/04 6.3%
22:52:11 : 05/05 3.1%
22:52:15 : 06/06 1.6%
22:52:21 : 07/07 0.8%
22:52:26 : 08/08 0.4%
22:52:31 : 09/09 0.2%
22:52:36 : 10/10 0.1%
22:52:44 : 11/11 0.0%
22:52:48 : 12/12 0.0%
22:52:59 : Test finished.
----------
Total: 12/12 (0.0%)
Horrid warbling and smearling like artifact at 1:22, just like on the Linchpin sample.
-q 0.60
foo_abx 1.3.4 report
foobar2000 v1.1
2010/09/06 22:55:21
File A: C:\Rips\Kraftwerk - Techno Pop\01. Boing Boom Tschak.flac
File B: C:\Temp\Boing Boom Tschak q 0.60.m4a
22:55:21 : Test started.
22:55:34 : 01/01 50.0%
22:55:42 : 02/02 25.0%
22:55:48 : 03/03 12.5%
22:55:52 : 04/04 6.3%
22:55:57 : 05/05 3.1%
22:56:05 : 06/06 1.6%
22:56:11 : 07/07 0.8%
22:56:16 : 08/08 0.4%
22:56:31 : 09/09 0.2%
22:56:41 : 10/10 0.1%
22:56:46 : 11/11 0.0%
22:56:52 : 12/12 0.0%
22:56:54 : Test finished.
----------
Total: 12/12 (0.0%)
The smearing artifact at 1:22 is gone, but at 1:10 - 1:11 an pre-echo artifact appears more obvious.
-q 0.50 vs -q 0.60
foo_abx 1.3.4 report
foobar2000 v1.1
2010/09/06 22:57:20
File A: C:\Temp\Boing Boom Tschak q 0.50.m4a
File B: C:\Temp\Boing Boom Tschak q 0.60.m4a
22:57:20 : Test started.
22:57:50 : 01/01 50.0%
22:57:56 : 02/02 25.0%
22:58:00 : 03/03 12.5%
22:58:07 : 04/04 6.3%
22:58:14 : 05/05 3.1%
22:58:19 : 06/06 1.6%
22:58:26 : 07/07 0.8%
22:58:32 : 08/08 0.4%
22:58:39 : 09/09 0.2%
22:58:44 : 10/10 0.1%
22:58:50 : 11/11 0.0%
22:59:00 : 12/12 0.0%
22:59:16 : Test finished.
----------
Total: 12/12 (0.0%)
I have compared both encodes between 1:09 - 1:11. I find the -q 0.50 encode sounds less annoying at 1:10, but the smearing at 1:22 sounds sounds pretty bad though.
Also it's ABXable at -q 0.80:
foo_abx 1.3.4 report
foobar2000 v1.1
2010/09/06 23:01:42
File A: C:\Rips\Kraftwerk - Techno Pop\01. Boing Boom Tschak.flac
File B: C:\Temp\Boing Boom Tschak q 0.80.m4a
23:01:42 : Test started.
23:01:57 : 01/01 50.0%
23:02:02 : 02/02 25.0%
23:02:06 : 03/03 12.5%
23:02:27 : 04/04 6.3%
23:02:34 : 05/05 3.1%
23:02:39 : 06/06 1.6%
23:02:46 : 07/07 0.8%
23:02:53 : 08/08 0.4%
23:03:00 : 09/09 0.2%
23:03:08 : 10/10 0.1%
23:03:13 : 11/11 0.0%
23:03:38 : 12/12 0.0%
23:03:40 : Test finished.
----------
Total: 12/12 (0.0%)